The present invention relates to the optical scanning of a code in series on a reglet and made up of retro-reflected elements at regular intervals. Sliding runners on the reglet each conceal a retro-reflecting mark and by their position indicate the code.
When reading the article code on a tote for transferring articles along a conveyor, the code typically passes a stationary code reader such that the elements making up each code bit occur in time sequence or serial sequence. In order to read the entire code accurately, typically storage means, such as a shift register, are provided which sequentially receives each code bit and stores the bit until the entire code is read and stored. Once this is done, the computer interface or whatever control utilizing the code reads the entire code out in parallel form (i.e., each bit simultaneously).
In order to shift each code bit serially into a storage device such as the shift register, it is necessary that a clock pulse be employed which has the effect of permitting each bit to be read and stored. There exist two generally known ways to generate clock pulses which, of course, must be in precise timed relationship to the code and, therefore, must in some way be related to the code strip carried by the tote. The first manner is to utilize a pulse generator driven by the conveyor which can be utilized since the speed at which the code on the tote passes the detectors is directly related to the conveyor speed. Another method which does not rely on conveyor speed information is to place a separate clock strip on the coded area on the tote. This, of course, requires an additional detector and associated circuitry, plus additional coding elements.